United States
                  Environmental Protection
                  Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
                  Research and Development
EPA/540/SR-95/505    May 1995
wEPA       Project  Summary

                  Removal  of RGBs  from
                  Contaminated Soil  Using  the CF
                  Systems® Solvent  Eixtraction
                  Process:  A  Treatability Study
                  Joseph Tillman, Lauren Drees, and Eric Saylor
                   The United States Environmental Pro-
                  tection Agency (EPA), through its Su-
                  perfund Technical  Assistance  Re-
                  sponse Team (START) and Super-fund
                  Innovative Technology Evaluation
                  (SITE) Programs, completed a treatabil-
                  ity study to determine the effectiveness
                  of solvent extraction in separating poly-
                  chlorinated biphenyls (PCBs) from soil
                  collected at the Springfield  Township
                  Dump (STD)  Superfund site near
                  Davisburg, Ml.
                   The study consisted of a total of six
                  runs, in which  100 Ib of dried soil was
                  processed for each run. Based on pre-
                  liminary analytical results, three 20-min
                  extraction cycles were chosen as the
                  most economical way to achieve the
                  project objectives. Therefore, this three-
                  extraction cycle condition was repeated
                  twice  to acquire data for three runs
                  operated at the same condition.  The
                  other three runs consisted of two, four,
                  and five 20-min extraction cycles.
                   The results  of the study indicated
                  that on average approximately 98 per-
                  cent removal of PCBs was achieved
                  for the test runs using three  extraction
                  cycles. The four-  and  five-extraction
                  cycle  runs were the most effective in
                  reducing the concentration of PCBs in
                  soil,  to 1.8 and 2.2 mg/kg,   respec-
                  tively. This indicated that the number
                  of extraction cycles required for attain-
                  ing the lowest concentrations of PCBs
                  in product solids was greater than three
                  but less than  or equal to five since
                  there was no discernible improvement
                  in PCB removal from four to five ex-
                  traction cycles. However, results from
oil and grease analysis  suggest that
high&r removal efficiencies may be pos-
sible with additional extraction cycles.
  Analysis of the filtered process wa-
ter collected from all six runs indicated
that PCBs were detected only in the
filtrate from the two-cycle run [1.9 mi-
crograms per liter [fig/L)]. PCBs were
not detected (<1.0 ng/L) in the filtrate
collected from the other five runs.
  This Project Summary was developed
by EPA's START and SITE programs in
Cincinnati, OH to announce key  find-
ings of a solvent extraction treatability
study  that  is fully documented  in a
separate report of the same title (see
Project Report ordering information at
back}.

Project Background
  EPA conducted a treatability study on
soil collected from the STD Superfund site.
The approximately 4-acre site  is located
near the town of Davisburg, Ml (Figure 1).
Between  1966 and 1968 the  STD was
used for  the disposal  of drummed and
liquid industrial waste.  Primary contami-
nants in the soil (a fine-to-coarse-grained
sand) include: arsenic,  lead, and barium;
volatile organic compounds (VOCs); and
semivolatile organic compounds (SVOCs),
which include RGBs and the pesticide di-
eldrin.
  Onsite incineration had been specified
in the Record of Decision for remediating
the soil at the site, but negative public
opinion toward incineration has led to the
consideration of treatment alternatives.
Based upon preliminary bench-scale test-
ing on  soil samples taken  from the site,
                                                                Printed on Recycled Paper

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                                                SPRINGFIELD
                                                TOWNSHIP *
                                                DUMP
Figure 1. Location of the STD Superfund site.
the CF Systems® (CFS) solvent extrac-
tion process was believed to be such an
alternative. Therefore, a treatability study
was conducted to determine whether the
technology would be effective in treating
soils at the STD to the desired cleanup
standard.
  Approximately 1,158 Ib of soil were ob-
tained directly from PCB "hot zones" at
the STD site and then screened onsite to
remove oversize  material (>1/2-in. diam-
eter), which  was approximately  168 Ib
(14.5  percent).  Of the approximately
1,000 Ib of material screened to <1/2-in.
diameter,  CFS used  approximately  150
pounds to conduct a series of bench-scale
tests in order to establish basic operating
conditions for the treatability study.  The
remaining volume was shipped to Hazen
Research,  Inc. in Golden,  CO, which is
the home base for CFS's Mobile Demon-
stration Unit (MDU).
  The treatability study  was  conducted
using CFS's pilot-scale MDU on a batch-
mode.  Liquified propane was the solvent
chosen to extract the organic compounds
from the STD soil. Figure 2 illustrates the
basic CFS process and the sample loca-
tions.
  At Hazen Research Inc., the feed mate-
rial was air-dried, further screened to re-
move oversize material (>1/4-in. diameter),
and mixed to produce a homogenous test
feed.  Table 1 summarizes the results of
the test soil screening for removal of over-
size material.
  The contaminated soil was fed in 100-lb
batches into the extractor and thoroughly
mixed with approximately 150 Ib of sol-
vent for each cycle. Following phase sepa-
ration  of the solvent and  contaminants
from solids, the solvent/contaminant mix-
ture passes from the extraction system to
the solvent recovery system. Once in the
solvent recovery  system, the  solvent is
vaporized  from  the contaminant,  con-
densed, and recycled back to the extrac-
tion system as fresh solvent. After all ex-
traction cycles  are completed, water is
added to the extractor and mixed with the
solids to aid in removing any residual pro-
pane. Product solids are discharged as a
slurry in water and then filtered to form a
filter cake.
Test Objectives and Conditions
  The primary objectives for the treatabil-
ity study were:

  • Determine the  effectiveness of
    removing PCBs from STD soil to the
    remedial action standard (RAS) of <1
    mg/kg.
  • Determine  PCB concentrations in the
    filtrate water to  ensure proper
    disposal.

  Secondary objectives of the treatability
study included but were not limited to veri-
fying  the absence of PCBs in the pilot-
scale unit prior to testing, determining re-
sidual  concentrations of  dieldrin  in the
product solids, and determining mass bal-
ance  for total materials.
  The CFS pilot-scale  treatability study
was conducted in  two phases, which in-
cluded a total of five  main process runs.
Phase I consisted of three test runs, each
consisting of a different number of extrac-
tion cycles. The first run consisted of three
20-min extraction cycles, the second run
consisted of four 20-min extraction cycles,
and the third run consisted of five 20-min
extraction cycles.
  Preliminary analytical results, using hex-
ane as the  extracting agent, indicated that
the primary objective  of producing solids
having <1.0 mg/kg  PCB concentration  was
met  for the three-cycle run.  Therefore,
Phase II consisted of two additional  test
runs using  three 20-min extraction  cycles
each, since this  process condition  was
believed to be the most economically  fea-
sible  in achieving the objective. It  was
later determined that these preliminary re-
                                                            - -^- Process Path Used for
                                                                Full-Scale System
                                                                Only

                                                             0 Solid Sample Location

                                                             £?; Liquid Sample Location
Figure 2. CF3S Process Diagram.

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 Table 1.  Percentage Of Screened Oversized Material
Location
Springfield Township Dump
Hazen Research Inc.
Starting
Material (Ibs)
1,158
-626
Material
Screened (Ibs)
168*
26»
% Oversize
~ 14.5
-4.0
                                  Total % oversize > 1/4nch
                                                                   ~18.Sc
 a Using plastic crating having approximately 1/2-inch openings.
 b Using an ASTM sieve having 1/4-inch openings.
 c Oversize material could be treated following size reduction (i.e., pulverizing) during a full-scale
  remediation.
 suits underestimated the concentration of
 PCBs in the treated soil.  A sixth  run
 consisting of two 20-min extraction cycles
 was added to test the limits of the pilot
 unit in treating soil to the desired levels.
 Table 2 summarizes the  process condi-
 tions for all six runs.

 Analytical Results
   Sampling was performed in accordance
 with an EPA-approved Quality  Assurance
 Project Plan. The critical process streams
 sampled for each of the six runs included:
 feed soil; product solids (filter  cake); and
 filtrate water. Samples of the organic ex-
 tract were taken  at the end  of Run 6, in
 order to perform a mass balance on PCBs.
   Table  3 summarizes the  MDU's PCB
 percent removal efficiencies  for each  run
 and as averages  of all six runs and  the
 three triple extraction cycle runs.  Oil and
grease (O&G) analysis was also conducted
on feed  and product solids for each test
run to determine  propane's capability  in
extracting semi- and nonvolatile organic
compounds in addition  to  PCBs. Results
of the O&G analyses are summarized  in
Table 4.
   PCBs  were not detected in the filtrate
samples collected for the  five main test
runs  (<1.0 ng/L).   However, for Run 6,
which involved only two extraction cycles,
PCBs were detected at 1.9 ng/L. The prod-
uct oil collected at the  end of the entire
study (3700 g) contained a PCB  concen-
tration in excess  of 11,000 mg/kg.  This
shows that the process was effective in
concentrating the PCBs  within the product
oil fraction.
   Dieldrin was not detected in the  feed
soil nor product solids; therefore removal
could not be evaluated.  More detail of the
 analyses  and  measurements are  dis-
 cussed in the Project Report.

 Mass Balance
   A total materials balance was conducted
 to account for all material loaded into the
 unit for each  run and to ensure that the
 majority of the  material was recovered
 and did not simply remain in one or more
 of the process components.  Any material
 loaded into the unit or exiting the unit was
 examined in the total materials mass bal-
 ance.
   Table 5  summarizes the results  of the
 total  materials balance for each run  and
 over the entire treatability study. Results
 indicate that approximately 98% of input
 material was accounted for in the product
 streams.  The mass balance closure for
 PCBs was approximately 62%.  The low
 recovery is believed to be at least partially
 attributable to the inability to drain all of
 the oil from the extract product tank  and
 associated piping.

 Quality of the Data
  The data quality objectives established
 for this pilot-scale treatability study were
 based on  project requirements  and thus
designed to ensure  that the data gener-
ated during the study would be of known
and acceptable quality to achieve  the
project's technical objectives.
  There were several quality control analy-
ses conducted to evaluate the laboratory
performance. These results are discussed
in  detail in  the  full  report.   The critical
 Table 2. Process Conditions For All Test Runs
Test Phase

1


II

Run No.

1
2
3
4
5
Feed
Loaded
(Ibs)

100
100
100
100
100
No. of
Extraction
Cycles

3
4
5
3
3
Mixing Time
Each Cycle
(min)

20
20
20
20
20
Mixing
Speed

Full
0/FulP
Full
Full
Full
Solvent/
Feed Ratio
(by weight
each cycle)
1.5/1
1.5/1
1.5/1
1.5/1
1.5/1
Extraction
Pressure
(psi)
Avg/Range
315/250-409
261/223-308
238/182-294
266/202-309
243/194-299
Extraction
Temp (°F)
Avg/Range

133/125-138
122/106-133
117/93-150
124/98-140
119/98-137
Added Run      6
                             100
                                                      20
                                                                      Full
                                                                                   1.5/1
                                                                                                 277/231-319     125/110-138
3 bottom. °ne °fthe f°Ur eXtraCt!°n CyCl8S' ^ miX6r WaS inoperable: however'a solvent «ow ™* established by recirculating propane from the top ofthe extractor into the


                                                              3

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Table 3.  PCB Removal Efficiencies
Run
Number
1
2
3
4
5
6
No. of
Extraction
Cycles
3
4
5
3
3
2
Soil Feed
Concentration1
(mg/kg)
210
240
340
3102
220
220
Product Solids
Concentration1
(mg/kg)
4.9
1.8
2.2
4.&
5.8
19.0
Percent
Removal
97.7
99.3
99.4
98.7
97.4
91.4
Average3
                                260/250
                                                        6.3/4.9
                                                                      97.6/98.0
 1 The test method used was SW-846 3540/8080; Aroclor 1254 was the only PCB identified.
2 Average concentration of analyses of field duplicate samples (see Table 7).
3 Two values are given; the first is the average of all six runs and the second is the average of the three extraction
  cycle runs (Runs 1,4, and 5).
Table 4. O&G Removal Efficiencies
Run
Number
1
2
3
4
5
6
No. of
Extraction
Cycles
3
4
5
3
3
2
Soil Feed
Concentration1
(mg/kg)
4480
4560
5870
5460
5140
7060
Product Solids
Concentration1
(mg/kg)
112
73
<20
133
93
279
Percent
Removal
97.5
98.4
>99.6
97.6
98.2
96.0
 Average2
5430/5030
                                                    <118/113
                                                                     >97.8/>97.8
 1 Tho test method used was SW-846 9071.
 2 Two values aro given; the first is the average of all six runs and the second is the average of the three extraction
   cycte runs (Runs 1,4, and 5).
target  analyte (PCB Aroclor 1254)  was
spiked into both a sample of the product
solids  and into a sample of the product
water to determine the accuracy and pre-
cision  for these matrices. The results of
these  matrix spike/matrix spike  duplicate
(MS/MS D) samples (Table 6) show that
accuracy and precision were obtained for
both matrix types and that the project qual-
ity assurance (QA) goals were met.
  Field  duplicate samples of raw feed,
product  solids, product oil, and product
water  were  collected  and analyzed for
RGBs.   Field duplicates provide a mea-
sure of precision for the combined samp-
ling and analytical processes. Table 7 pre-
sents  these  results, which  show that the
project relative percent difference (RPD)
goal of 40 was easily met.
   It should  also be mentioned that PCBs
were not detected in any of the laboratory
method  blanks,  nor in  a rinsate sample
collected from the pilot plant prior to the
study, indicating  that contamination was
not a problem.

Conclusions
   The analytical test data indicate that the
primary goal of producing solids having a
<1.0 mg/kg PCB concentration  was not
attained  by  the designated  test method
used.   Of  the five main  test  runs, the
closest PCB concentration to the HAS was
 1.8 mg/kg in Run 2 product solids, which
was approximately a 99.3 percent removal
efficiency. The average PCB removal ef-
ficiency attained for the three-extraction
cycle  test runs was 98%.
   There is not enough PCB data to indi-
cate whether the additional fifth extraction
cycle  conducted  during Run 3  benefited
 Table 5. Total Materials Balance

Run
Number
1
2
3
4
5
6
Total
Input (grams)
Feed
Soil1
45,400
45,800
45,800
45,800
45,800
45,800
274,400
Water

52,600
80,800
93,800
88,500
99,500
103,000
518,200
TOTAL

98,000
126,600
139,600
134,300
145,300
148,800
792,600
Output (grams)
Oil Extract

	
	
	
	
	
3,700
3,700
Slurry

71,600
147,400
1 16,200
134,800
141,200
158,800
770,000
F-1 Filter
Solids
485
485
485
640
640
640
3,380
Total3

72,090
147,900
116,700
135,400
141,800
163,100
777,000
(%) Recovery
Material

73.6
1172
83.6
101
97.6
110
98
 1 Runs 2-6 Includs the addition of 454g of sand to fill void space in the extractor.
 2 Solids not flushed out In Run 1 exited at the end of Run 2.
 3 Totals rounded to four significant digits.

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Table 6. PCS Aroclor 1254 Matrix Spike/Matrix Spike Duplicate (MS/MSD) Results
Sample
Spike
Sample Cone.
                                                          MS
                                                 MS%R
                                                                                         MSD
                                                                MDS % R1
                                                                                           RPD*
Product Solids
Filtrate
4.9 mg/kg
10.0 ug/L
4. 1 mg/kg
< 1.0 ug/L
8.2 mg/kg
9.0 iig/L
84
90
9.1 mg/kg
7.8ng/l.
102
78
10
14
1 The OA objective for accuracy was a recovery of 50-150 percent.

                         C'-C,
             % Recovery --
                                 x 100
                                                 where,
2 The OA objective for precision was an RPD of<40.

                     (Maximum Value - Minimum Value)
                                                          C1 is the measured concentration in the spiked sample
                                                          C0 is the measured concentration in the unspiked sample
                                                          C, is the known concentration ofanalyte added to the sample
             HPD
                     (Maximum Value + Minimum Value)/2
                                                  x  100
Table 7.  PCS Aroclor 1254 Field Duplicate Results


Sample Matrix         Sample Result
                           Result 2
                                               RPD'
Feed
Product Solids
Product Oil
Filtrate
350 mg/kg
4.0 mg/kg
1 1,200 mg/kg
< 1 ug/L
260 mg/kg
3.9 mg/kg
1 1,300 mg/kg
< 1 ug/L
30
2.5
0.9
NC
 '  The project objective for precision was an RPD of<40.
 NC = Not calculated
 PCS removal beyond the four-extraction
 cycles conducted during Run 2. The two
 concentration values, for Run 2 (1.8 mg/
 kg) and Run 3 (2.2 mg/kg), are essentially
 equal since they are within the range of
 field sampling and analytical error.  How-
 ever the  O&G analytical results can be
 used to supplement the interpretation of
 results, with respect to organics removal
 in general.   As Table 4  indicates, when
 the  O&G data is  evaluated, the five-ex-
 traction cycles used for Run 3 appears to
 have performed the  best for overall or-
 ganics removal.
   The performance of the runs relative to
 one another is illustrated in  Figures 3 and
 4. These show the removal of RGBs and
 O&G, respectively, for each test  run  as
 the  decline in contaminant  concentration
 from starting feed to product  solids  as
 sloped lines.  Both figures  show the dis-
 parity in  performance between test runs
 for the respective parameters, which may
 not  be as apparent when simply  looking
 at percent removal values. Figure 3 clearly
 shows that Runs 2, 3, and 4 came closer
 to  the  test  objective,  assuming  a feed
                   concentration  equal to the average of all
                   runs (250 mg/kg). Their slopes essentially
                   parallel one another. Figure 3 also shows
                   that Runs 1 and 5 had an almost identical
                   performance and that Run 6 had the poor-
                   est performance.  For O&G removal, Fig-
                   ure 4 indicates that Run 3  produced the
                   "cleanest" solids, while Runs 1, 2, 4, and
                   5 had similar performance.  Again, Run 6
                   had  the  poorest performance, indicating
                   that greater than two extraction cycles are
                   required to achieve O&G removal efficien-
                   cies > 96%.  These results suggest that
                   the extraction  process  operating condi-
                   tions could be further optimized to yield
                   higher removal efficiencies than were iden-
                   tified in this study.
                     Another important conclusion that re-
                   sulted  from  the study regarded the vol-
                   ume reduction of hazardous  waste.  Al-
                   though the  CFS solvent  extraction pro-
                   cess is not  capable of  destroying  PCBs
                   and other contaminants present in the STD
                   soil (as is the case with solvent extraction
                   technologies in general), it is a means of
                   separating  those contaminants  from the
                   soil, thereby  reducing the volume of haz-
                                               ardous waste that must be treated. This in
                                               turn reduces the cleanup costs involved.
                                               The cumulative mass of the wet contami-
                                               nated feed soil for all six runs of the treat-
                                               ability  study   was  approximately
                                               274,000 g.  The mass of the oily extract
                                               sampled at the completion of Run 6 was
                                               approximately 3,700  g.   Therefore,  the
                                               process reduced the overall mass of the
                                               contaminated material to 1.35% of its origi-
                                               nal waste mass.  The  volume of the feed
                                               soil [SG=1.34  g/mL and oil  extract
                                               (SG=0.87 g/mL)  were approximately 204
                                               and 4.3 L,  respectively.  Therefore,  the
                                               process reduced the overall volume"of the
                                               contaminated material to 2.1% of its origi-
                                               nal  waste volume.  The highly concen-
                                               trated oil extracted from the CFS process
                                               is  either destroyed  by incineration  or
                                               chemical dechlorination.   ~
                                                  The full report was submitted in fulfill-
                                               ment of Contract No. 68-CO-0048, Work
                                               Assignment No. 0-50, by  Science  Appli-
                                               cations International Corporation under the
                                               sponsorship of the U.S. Environmental Pro-
                                               tection Agency.

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                 300
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                 100-
                                                   MJ  Run No.
                                                  — — . Test Objective
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                                                  —•—  4 extraction-cycle run
                                                  ——  5 extraction-cycle run
                                                  	2 extraction-cycle run
                         12345
                                          i	1	—
                                         10                  15
                           Product Solids Concentration (PCBs in mg/kg)
                                                                                               20
  Figure 3.  PCB removal trend.
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Figure 4. Oil & grease removal trend.

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Joseph Tillman, Lauren Drees, and Eric Say/or are with Science Applications
  International Corporation in Cincinnati, OH 45203.
Mark Meckes is the EPA Project Officer (see below).
The complete report (Order No. PB95-199030; Cost: $19.50, subject to
    change) will be available only from:
        National Technical Information Service
        5285 Port Royal Road
        Springfield, VA 22161
        Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
        Risk Reduction Engineering Laboratory
        U.S. Environmental Protection Agency
        Cincinnati, OH 45268
  United States
  Environmental Protection Agency
  Center for Environmental Research Information
  Cincinnati, OH 45268

  Official Business
  Penalty for Private Use
  $300
     BULK RATE
POSTAGE & FEES PAID
         EPA
   PERMIT No. G-35
 EPA/540/SR-95/505

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